Micro-electronic circuits and other micro-scale devices are generally manufactured from a substrate or wafer, such as a silicon or other semiconductor material wafer. Multiple metal layers are applied onto the substrate to form micro-electronic or other micro-scale components or to provide electrical interconnects. These metal layers, e.g., copper, are plated onto the substrate, and form the components and interconnects in a sequence of photolithographic, plating, etching, polishing or other steps.
To achieve desired material properties, the substrate is typically put through an annealing process in which the substrate is quickly heated, usually to about 200-500° C. and more typically to about 300-400° C. The substrate may be held at these temperatures for a relatively short time, e.g., 60-300 seconds. The substrate is then rapidly cooled, with the entire process usually taking only a few minutes. Annealing may be used to change the material properties of the layers on the substrate. It may also be used to activate dopants, drive dopants between films on the substrate, change film-to-film or film-to-substrate interfaces, densify deposited films, or to repair damage from ion implantation.
As feature sizes for microelectronic devices and interconnects become smaller, the allowable defect rate decreases substantially. Some defects result from contaminant particles. Other defects can result from incomplete processing of certain regions of the wafer, e.g., failure to grow a film at the bottom of a trench.
Various annealing chambers have been used in the past. In single wafer processing equipment, these annealing chambers typically position the substrate between or on heating and cooling elements, to control the temperature profile of the substrate. However, achieving precise and repeatable temperature profiles, as well as an acceptable level of defects, can present engineering challenges.